Traditionally the molded skins for making doors of the type disclosed in U.S. Pat. No. 3,950,894 issued to DiMaio and U.S. Pat. No. 4,550,540 issued to Thorn are constructed by weight of polyester resin 12% to 15%, polystyrene 5% to 15%, calcium carbonate 40% to 50% and chopped fiber glass 15% to 25%. Such a mixture is placed in layer in a compression molding machine where it is subjected to pressures from 600 to 1,500 psi for a cure period from 60 to 200 seconds. The mixtures are usually referred to `sheet molding compounds` SMC! and are normally thermoset materials such as phenolics, urea, melamines and polyesters. A general description of the process is found in an article entitled, "Compression Molding" by N. D. Simons in Modern Plastics Encyclopedia, Vol. 54 No. 10A (1977-78).
The result of the SMC process is a skin having a thickness of from about 0.05 inches to about 0.20 inches, depending on the application, which can be use in the doors of the type referenced. However, the prior art skins when removed from the mold have pale gray, streaked appearance. Thus, doors, and other products constructed with such prior art skins must be painted or stained to achieve a product which is architecturally acceptable.
Staining or painting such door products is expensive and time consuming; further the surfaces of such skins is not very porous, often requiring expensive materials or processes to paint them. Further such painted or stained door products may become scratched or abraded in use whereby they may look tacky and cheap after installation.
Another draw back of such prior art door products is that staining or painting may obscure patterns impressed on the exterior of the surface of the skins during the molding process.
In addition, when using skins which are stained or painted, the edges when trimming is required exposes areas of discoloration.
With the instant invention the color is distributed uniformity throughout the skin, whereby scratches and abrasions will not to be so apparent during service and trimming the skins will not result in a variegated or streaked door structure with color discontinuities in the area where the trimming occurs.
Further actual tests of the doors using skins made according to the instant invention have shown improved weathering characteristics under ASTM G26 testing procedures over the conventional stained or painted doors of a similar construction.
It has been found that certain pigments may be added to the conventional raw materials used to manufacture skins of the type described without degrading the resulting skin product formed through or by the compression molding processes whereby a multitude of colors can be achieved. In this regard, titanium oxide, ferric oxide, chromium oxide and carbon black in mixtures, or as individual components, can be added in quantities up to 20% without degrading the skins.